QUIZ 2: Tooth Protection - Base and Liners

What are bases and liners used for? (3)

1. To protect the pulp of the tooth

2. Helps with post op sensitivity and pulpal prognosis --> goal is to prevent irreversible pulpitis

3. Intermediate restorative materials - sandwiched between the cavity preparation and restorative material

Describe reversible pulpitis

Mild to moderate inflammation of the pulp caused by a stimulus

Pulp is capable of returning back to an uninflamed state

Describe irreversible pulpitis

Persistent inflammation of the pulp --> symptomatic or asymptomatic

Pulp is incapable of returning back to an uninflamed state

What are the types of stimulus that pulp responds to?

1. Physical --> thermal, electrical

2. Mechanical --> handpiece, traumatic

3. Chemical --> acid etch

4. Biological --> bacteria

What happens to dentin when we prepare a tooth?

it becomes more exposed

What is tooth sensitivity directly related to?

the size and patency of dentinal tubules

What helps decrease tooth sensitivity?

Sealing or occluding dentinal tubules

reducing dentin permeability and fluid flow

What reduces the flow of fluid to the tooth?

occluding the tubules either by:

1. peritubular dentin deposition OR

2. introduction of intra-tubular material

(irregular reparative dentin does this naturally)

What is a dental liner?

thin layer placed over the exposed dentin within a cavity preparation

What are the functions of a dental liner?

Seal the dentin

Protect the pulp from stimuli

Stimulate formation of tertiary dentin

What is the thickness of a dental liner?

0.20 - 0.75 mm

Does a dental liner have bactericidal/anticariogenic qualities?

yes

What is the strength of dental liners?

low

Is a dental liner moisture sensitive?

yes, doesn't like moisture

What is the ideal formula of a dental liner?

Low thermal conductivity

Easily to manipulate and place

Highly soluble

Comes as a catalyst and a base system or light-cured material

What are the types of dental liners?

Varnish

Calcium hydroxide

Resin-Modified Calcium Silicate

Zinc phosphate

Glass Ionomers

Resin

What are the properties of calcium hydroxide?

Most commonly used liner today

Protects the pulp from chemical irritation by sealing

Compatible with ALL types of restorative material

Stimulates the formation of tertiary dentin

Can also be used for indirect/direct pulp capping

What are the properties of Resin-Modified Calcium Silicate?

Light cured

Tolerates moisture and does not break down over time

Protects the pulp from chemical and thermal irritation

Compatible with ALL types of restorative material

Stimulates the formation of tertiary dentin

Can also be used for indirect/direct pulp capping

Where do we place a dental liner?

Placed on the deepest part of the dentin surface

Closest to the roof of the pulp chamber

Not placed on enamel or in retentive grooves

SUMMARY: What are the main purposes of a dental liner?

protect pulp and create tertiary dentin

What is a dental base?

Thicker layer placed on the floor of a cavity preparation

What are the functions of a dental base?

Lower post op sensitivity

Lowers thermal conductivity

Help absorb occlusal forces

Prevents dentin permeabliity

SEALS DENTINAL TUBULES

What is the thickness of a dental base?

0.75 mm (at least)

What are the types of dental bases?

Zinc oxide eugenol (low strength)

Zinc phosphate (high strength)

Zinc polycarboxylate (high strength)

Glass ionomers (high strength)

Resin (high strength)

Should you place a dental base directly on the dentin?

no, it doesn't create tertiary dentin

place liner first

What is the strength of a dental base?

with a single layer, it will be strong

adding more doesn't necessarily increase the strength

What is a dental base compatible with?

dentin, pulpal, and restoration

What are some characteristics of dental bases?

Should not irritate pulp

Should not discolor

Easy to manipulate and place

Why is a glass ionomer best for dental bases?

Most commonly used base today

High compressive strength

Bonds to tooth structure

Similar expansion to the tooth --> helps reduce microleakage and sensitivity

How do we place a dental base?

Placed along the entire pulpal floor of the preparation

Is a varnish or sealer placed over the base?

sometimes, glass ionomer may help desensitize and release fluoride

When is etch/bond placed if composite is being used?

after placement of base

What is the purpose of dental desensitizer/sealer?

Providers a protective barrier between tooth and restorative material

Can help prevent/reduce postoperative sensitivity

Improves collagen stability

Stiffens dentin

Improves bond strength

What are the 3 main functions of Gluma?

Helps kill bacteria

Seals dentinal tubules

Re-hydrates collapsed dentinal tubules

How does Gluma seal dentinal tubules?

Creates protein plugs

Prevents movement of fluid

Is Gluma compatible with adhesives?

yes

How do you apply a desensitizer/sealer?

Tooth is etched, rinsed, dried

Material is applied using a microbrush

- 2-3 layers is usually adequate

- Air dry lightly

Primer and resin are then placed as normal

What is the main goal of bases and liners?

PREVENT PULPAL DAMAGE

ALLOW FOR TOOTH PROTECTION

CREATE AN ENVIRONMENT TO PROMOTE HEALING